In general, a vacuum cleaner for removing dust on a floor surface or the like is configured to suck air therein and capture and collect the dust in the sucked air.
As the dust collection method thereof, a method of providing a detachable bag that also functions as a filter and, when the bag has been filled with the dust, replacing the bag with a new bag has become mainstream.
Moreover, in addition to this, a cyclone portable vacuum cleaner, a rechargeable portable vacuum cleaner, a self-propelled vacuum cleaner called a robotic cleaner, and so forth are used.
As an example of the self-propelled vacuum cleaner, robotic cleaners described in PTLs 1 and 2 have been proposed.
The self-propelled vacuum cleaner is provided with a rechargeable battery, and, separately from the vacuum cleaner, a charging base is fixedly placed in a predetermined position.
The self-propelled vacuum cleaner cleans a room by autonomously travelling when the remaining level of the rechargeable battery is more than or equal to a predetermined value.
Moreover, there is a self-propelled vacuum cleaner that searches for the position of the charging base, while autonomously travelling, when the remaining battery level becomes less than or equal to a predetermined value and, when finding the charging base, travels toward the charging base and recharges the rechargeable battery by connecting the rechargeable battery thereof to the charging base.
The search for the position of the charging base is performed by the detection of an optical beam emitted from the charging base with a light receiving element.